1. Field of the Invention
The present invention relates to television camera or other output data systems and, more specifically, to camera output data systems which convert sequentially digitized interlaced data from a television camera or other data source into non-interlaced form for storage in a memory.
2. Description of the Prior Art
In modern digital electronic imaging systems, typically used in machine vision part quality inspection and measurement applications, etc., the analog output data from a television camera which corresponds to a digitized visual image is stored in digital form in a computer memory for subsequent comparison with pre-set values, dimensions and other image algorithm operations, as well as enabling such data to be enhanced to provide increased clarity, filtered to decrease noise, enhance edges and further matched against stored template images or otherwise mathematically manipulated.
In normal operation, a camera scans the field of vision or frame line by line. Each scan line has a finite resolution limit which can be effectively represented by a number of light responsive picture elements or pixels. The number of scan lines and the number of pixels per frame vary depending on the resolution capabilities of each camera. For example, cameras may have 256 pixels per scan line and 256 scan lines per frame. Analog video outputs from high resolution cameras are often able to be digitized such that they provide 512.times.512 or 1024.times.1024 pixels per scan line by scan lines per frame.
In operation, as the camera sequentially outputs each scan line, analog voltage values are generated corresponding to the incident light integrating an electrical charge at each particular location on the camera photosensitive element. These values are converted, usually in a host computer containing a high-speed analog to digital converter, into digital form, typically, but not limited to, between 0 and 255 values on the gray scale, to provide an indication of the intensity of the image of each particular picture element or pixel.
Historically, television camera scan rates developed as a result of then current CRT phosphor persistence, deflection electronic characteristics and other complexities, etc., resulting in the development of standards, such as EIA RS170A, NTSC, CCIR, and others. EIA is an acronym for the Electronic Industries Association RS170A, a subset of the NTSC (National Television Systems Committee standard). European countries use the international CCIR (Consultive Committee International Radio) standard which is similar to but not compatible with the RS170A standard. These standards led to interlacing of camera output data in which an odd field and an even field of video information is generated at a rate of 1/50.sup.th to 1/60.sup.th of a second per field.
Each odd field contains data corresponding to each pixel in each odd numbered scan line on a sequential basis as shown in FIG. 1. FIG. 1 illustrates the sequential output from the camera, with each dot representing one pixel data value in each scan line. Thus, the camera outputs data on the odd numbered scan lines (i.e. 1, 3, 5, etc) for each frame followed by the even numbered scan line data (i.e., 2, 4, 6, etc.). In by the even numbered scan line data (i.e., 2, 4, 6, etc.). In machine vision applications, the camera output is digitized and stored in a memory in odd and even blocks identical to that shown in FIG. 1 as the data is received by the memory with the whole even numbered scan line data following the odd numbered scan line data.
This separates the data corresponding to vertically adjacent pixels in the image from each other within the computer memory and leads to difficulties when such vertically adjacent pixel values must be mathematically or otherwise manipulated for image enhancement, correlations, filtering, measurement or other similar imaging operations. Such procedures usually involve comparing a particular pixel value with its surrounding pixel values or changing a pixel value relative to its "neighborhood" pixels. The computer processing required to select the appropriate pixel element values for processing is made more complex due to the separation of the odd and even field pixel values within the computer memory resulting in larger programs as well as a slower processing time. This reduces computer throughput which can effectively slow down part production when a machine vision system employing such an imaging system is used in a real time environment.
Thus, it would be desirable to provide a data converter which overcomes the problems with previously devised data converters in managing camera output data. It would also be desirable to provide a data converter which stores interlaced digitized, sequential camera output data in a computer memory in a manner which enables easy manipulation of such data for subsequent processing. It would also be desirable to provide a data converter which stores sequential, digitized interlaced camera output data in a computer memory in a non-interlaced form in real time with no additional computer processing time required. Finally, it would be desirable to provide a data converter which stores interlaced camera output data in a non-interlaced matter in a computer memory and, yet, enables such data to be read out for further processing or for display on a monitor in either of an interlaced or non-interlaced form.